This invention relates to supporting means for elongated building services supply means. Such service supply means may be electric power cables, communication cables, water or gas pipes or other elongated means for the supply or distribution of services within a building. Such supporting means necessarily include one or more bearer elements on which the service supply means rest. Typically the bearer element has been the floor of a tray or trough fixedly associated with the building being serviced, for example carried by wall brackets or suspended from a ceiling or other overhead building component by tie rods or the like. Probably the most frequently occurring service supply means are electric cables, and for that reason, supporting means of the kind to which the invention relates are usually referred to in the art as xe2x80x9ccable traysxe2x80x9d, irrespective of the service supply means that may be supported in any instance, and notwithstanding recent departures in the form of the bearer elements from that of an integral floor of a traditional tray or trough. When convenient that term of art is used accordingly hereinafter.
As stated above, traditionally the bearer elements of cable trays comprised the floor of a shallow trough or elongated tray. The service supply means resided within the trough. The trough including its floor was constructed from sheet material, for example steel, plastics or fibrous cement.
Alternatively, at least the floor of the trough has been made of expanded metal sheet. This is preferred as it eliminates the possibility of the trough retaining water or detritus that may be damaging to the service supply means.
In other instances floor-like bearer elements came to be replaced by a plurality of spaced apart rungs extending between rigid stiles. The wall brackets or tie rods are affixed to the stiles, so that the supporting means as a whole resemble a conventional ladder in a substantially horizontal disposition. Such ladder-like supporting means are still customarily referred to as cable trays.
In more recent times, the stiles of such ladder-like cable trays have been replaced by a central spine, and the rungs by a plurality of spaced apart bearer elements extending as cantilevers from each side of the spine. The bearer elements preferably have upturned free end parts, so as to retain the service supply means. This is advantageous as the service supply means may be placed on the bearer elements from the sides, instead of having to be pulled into position from one end of the cable tray.
The last mentioned prior art is well exemplified by the published specification of Australian patent application 99/943515 and the International publication WO 98/24160 of International application PCT/AU/00788 (both in the name of Ramset Fasteners (Aust) Pty Ltd). In that cited cited prior art the spine is a rectangular sectioned tube, and the cantilever bearer elements extend through clearance openings piercing the tube walls. It is apparent that the upturned free ends of the cantilever bearer elements are formed after the elements have been passed through those openings, otherwise it would not be possible to put them in place. This is disadvantageous, as it would require expensive manual operations or the use of complex special purpose machines in the manufacture of the cited prior art cable trays.
An object of the present invention is to alleviate the aforesaid disadvantage of the prior art. A further object is to provide for the on-site selection of the spacing between discrete bearer elements to suit the degree of pliability of the service supply means in any instance.
The invention is well adapted for use in relation to cable trays comprising a single spine and a plurality of discrete cantilever bearer elements, although it will be apparent to the skilled addressee that it is also applicable to ladder-like cable trays having two or more parallel spines and a plurality of discrete rung-like bearer elements.
The invention, in its broadest aspect, consists in supporting means for elongated building service supply means of the kind comprising at least one spine and a plurality of discrete bearer elements affixed to said at least one spine, characterised in that each bearer element is affixed to said at least one spine by a spring clip fixedly associated with said each bearer element.
For preference the spring clip is formed integrally with its associated bearer element.
According to a second aspect, the invention consists in supporting means according to the first aspect wherein there are at least an equal plurality of locating formations on said spine each able to be engaged by a co-acting locating formation on a said spring clip to thereafter resist disengagement of the bearer elements from the spine.
In preferred embodiments of the second aspect of the invention the spine is an inverted channel section comprising a channel web and two channel flanges, said locating formations comprise a longitudinally extending row of spaced apart holes in each of the channel flanges, each spring clip comprises two upwardly directed, spaced apart resilient tongues projecting from the clip""s associated bearer element, each with a barb formation at or near its free end directed towards the other and each with a stud intermediate its ends projecting towards the other constituting said co-acting locating formations; the arrangement being such that the tongues of each clip may clasp the spine between them with the barbs of the tongues overlying respective margins of the channel web and with the studs on each tongue extending into a respective hole in the adjacent channel flange.
Furthermore, for preference, in the last mentioned embodiments each bearer element defines a groove at or near the root of each of its tongues in which a free edge margin of the adjacent channel flange is received when the barb formations overlie the margins of the channel web and the studs are homed in the holes.